Twin disc MG 502 Disassembly ???

[kneeslider74]

I am ready to fix a leak in the case and have never opened one of these up. From what I can tell I think I can stand it on the tail and once the bolts are removed from the case, remove the bell housing then the seal, then the collar, and a snap ring and a couple of washers to pull the front half of the case off.

I do not see any other way to get the case split.
Can anyone confirm that this is the way to get in there and anything to watch out for when I get it apart.
Thanks

[MILD THUNDER]

Prob wont find that many on here that are familiar with the twin disc tranny. Maybe a cruiser forum, or send KVogt on here a pm. I think he is familiar with them. Im guessing you have Kaama drives on that unit.

[kneeslider74]

Yep Kamma cat. I have a small leak I wanted to fix before I put in the new motors. I looked it over and searched the web but it is difficult to tell how they come apart and I don't want to F*@& anything up.

Do you know what Hp the Kaama's will handle? I dynoed at 750HP & 675 Trq @ 3psi and was considering a pulley change to 9 psi and I am afaid that 850 may be a bit much. Penny for your thoughts.
Thanks for the lead.

[MILD THUNDER]

I been drinking, but I think the weak link is the stock twin disc trans in the kaama setup

[kneeslider74]

Any recomedation for replacment transmissions when I blow them up?
Do you know if they can be beefed up?
Thanks

[dereknkathy]

there is a twin disc MG 506 manual on ebay. 20 bucks plus 6 ride. hereis iem number; 370577126545

[I'CE]

Kamma drive rated @ about 700HP seen guys put over 900 thru. the trans and drives with survival. I think the trans. was beefed up some what for this application. Archer Marine, Costa Mesa, California might be able to advise. Call Nopper Marine, Fairhaven, MA 508-993-5050 he "Peter" may have knowledge. PM me your phone # if ya want to chat, can fill ya in on some data as well.

[kneeslider74]

OK, I just decide to jump in and see what happens. I got the cases split but it was a learning curve which I will share.
I first removed all the case bolts and a vouple that go through the selector on the back. I turned the unit over on 2 2X4's, and took after it with a pry bar to seperate the cases,,,, this did not work , as I learned that the output bearing is either pressed in or tight fitting. So after some swearing I got enough space between the cases to prop the pry bars up and keep pressure on the case while I tapped( hit really hard) the output shaft. Similar to how you remove a steering wheel without a puller, and still would not come aprt completely. Ahhh there is a shield inside that must come loose with 2 bolts to remove. Once I did that it popped apart. I then realized how hard it was going to be to get that shield back in and uep I was right agian,,,what a pain in the fingers!
Just a note of caution, don't hit the seal or you will be out 30 bucks, Ooops.
I hope this helps, and I don't know if there is an easier way but this is info that I wish I had.
Good luck and happy boating.

[Raylar]

Not sure why you guys sometimes seem to like to learn from struggling with a piece. My learning has taught me to email or call a manufacuter or distributor of Twin Disc marine transmissions and either download the service manual or buy one for a small dollar amount and READ THE INSTRUCTIONS for opening the unit and servicing it! Guess I am just kinda to old to make it more difficult than that.

Best Regards,
Ray @ Raylar

[Car Biz]

OK, I just decide to jump in and see what happens. I got the cases split but it was a learning curve which I will share.
I first removed all the case bolts and a vouple that go through the selector on the back. I turned the unit over on 2 2X4's, and took after it with a pry bar to seperate the cases,,,, this did not work , as I learned that the output bearing is either pressed in or tight fitting. So after some swearing I got enough space between the cases to prop the pry bars up and keep pressure on the case while I tapped( hit really hard) the output shaft. Similar to how you remove a steering wheel without a puller, and still would not come aprt completely. Ahhh there is a shield inside that must come loose with 2 bolts to remove. Once I did that it popped apart. I then realized how hard it was going to be to get that shield back in and uep I was right agian,,,what a pain in the fingers!
Just a note of caution, don't hit the seal or you will be out 30 bucks, Ooops.
I hope this helps, and I don't know if there is an easier way but this is info that I wish I had.
Good luck and happy boating.

Great Lakes Power Products in Taylor MI. 734-946-7401

They are a Twin Disc dealer. I bought my clutch packs from them. They should habve everything you need to rebuild one. I had Steve Rescorla from here in GR rebuild mine.

BTW they are a STRONG tranny. Twin Disc says rebuild time is 700hrs BUT that is only after "continus max rpm"